Sciencemadness Discussion Board

Hydrofluoric Acid experiments

oneup - 2-1-2006 at 06:01

A few days ago I learned that >95% sulfuric acid could displace acids from their salts.
So I thought I might be able to displace Hydrofluoric Acid (HF) from Sodium Fluoride (boil down from mouthwash solution.)
The reaction should go like this:
H2SO4 + NaF --> HF + NaHSO4

Hydrofluoric acid is an extremely dangerous chemical, capable of dissolving glass. Now that's something i've gotta try! :P
MSDS: Click

Molarity of >95% Sulfuric Acid is 18, so to get 1 mole we need 1/18 = 0.0555
0.0555 * 1000 = 55.5mL
Molar mass of Sodium Fluoride is 42g/mol, so 55.5ml Sulfuric Acid and 42g Sodium Fluoride.
I think about doing to expirement in a plastic container or so, or anything that H2SO4/HF can not dissolve.

Nerro - 2-1-2006 at 06:04

You are aware that you will be making HF(g) right?? If you make HF please do it in water so the HF stays in solution and use every precautionary measure possible even if it may seem rediculous because this stuff is about as nasty as they come.

[Edited on Mon/Jan/2006 by Nerro]

oneup - 2-1-2006 at 06:11

HF boils at 19C so if I use an ice bath I will be making HF(l)
and if i do it in water i will be diluting the sulfuric acid and it no longer works.

gsd - 2-1-2006 at 07:11

you will have to distill the HF gas out of reaction mixture and then dissolve it in water in separate container.

you can refer to the aparatus and procedure for making gaseous HCl from liquid HCl and conc. H2SO4 in any std. organic synthesis text book (e.g. Vogel.)

plastic won't do for this job but you can use mild steel.

Ice bath doesn't make sense as when you add >95 % H2SO4 to an aquous solution, heat of dilution is so much that the mixture comes to boiling. Ice bath will not keep the "intrinsic temperature" below 19 Deg. C. even if overall reaction mixture temperature may remain below 19.

chromium - 2-1-2006 at 07:42

I do not think that steel can be used for distilling HF. This distillation can be done only in lead or platinum retort (lead retort can be made from lead tubing).

In my opinion its mad idea to make HF without lots of experience with less dangerous fluids. Nitric or hydrochloric acid are more usefull in lab and a lot more safe. There are not many interesting things that can be done with HF. Glass can be dissolved with fused NaOH or even with hot sodium silicate as well and this is almost all (expect in case you want to do some specific metalwork where only HF can be used as cleaner or solvent).

gsd - 2-1-2006 at 08:43

Industrially Mild Steel (MS) is used for handling HF Vapours. It forms a passive layer on the contact surface and prevents any further corrosion.

Microtek - 2-1-2006 at 08:48

Even dilute sulfuric acid will work. It will be somewhat safer to add NaF to dilute H2SO4 and then distill this mixture. That way you will end up with dilute HF. The concentrated acid ( HF ) is not primarily dangerous because of its corrosiveness but because of its toxicity. Placing a drop of HF on the skin of some kind of animal ( I don't know which mammal they used; probably rabbit or rat ) caused a moderate burn, but killed the animal due to fluoride poisoning.
I also remember reading about an amateur experimentalist who accidentally knocked over a beaker of dilute HF, spilling it into his lap. Realising the potentially lethal nature of his accident, he jumped into a nearby swimming pool and tore off his clothes in the water. He was immediately hospitalized, but died a few days later anyway.

In short, I reccomend that you stay away from this one - or if you must, experiment with much smaller amounts of dilute material ( less than one gram of NaF ).

woelen - 2-1-2006 at 10:37

Oneup, it is nice to be a mad scientist, but please be not mad. HF is not something to think of lightly. If handled carelessly, it will kill you, slowly and painfully. Many great scientists from the past such as Davy, have suffered terrible pains. Have a read of this:
http://www.lateralscience.co.uk/Fluorine/Fluorine.html (the entire site is a nice read on its own, but don't try these things at home :D).

If you really want to do some experiments with HF, then simply dissolve some NaF in dulute H2SO4 or dilute HCl and then use that liquid to etch some glass. There is no need to distill off the HF, the chloride (or sulfate) and sodium ions do not interfere. But please do not play around with gaseous HF if you value your health. As a young boy I already had NaBr, KBr, NaI, KI and of course NaCl and KCl, and I also wanted NaF and/or KF, but thank God I did not have access to NaF 20 years ago in my younger and unwise years :P. Fluoride is not just another halogenide, like the others.

Even the aqueous solution must be handled with extreme care. I bet I prefer having concentrated HCl on my skin than having dilute HF at my skin. This stuff is soooo nasty.

Darkblade48 - 2-1-2006 at 10:45

I wouldn't even dream of working with HF unless I had a bottle of calcium gluconate nearby (think on your belt loop or something). HF burns are very nasty indeed.

chromium - 2-1-2006 at 14:39

Does anyone know what is "safe" dose of HF when absorbed through skin? I know that small drops do not kill just make burns that turn very painful after some hours or a day.

Some mouthwashing liquids contain sodium fluoride and our stomatch contains acids. How is that this combination is not dangerous? Can anyone explain?

[Edited on 2-1-2006 by chromium]

woelen - 2-1-2006 at 14:47

The fluoride in commercial mouth washing liquids and also in tooth-pastes is present in very small amounts. At most a few 100's of ppm. Even then it is not advised to swallow these, but just use them to rinse your mouth (or brush your teeth). For this reason, children's tooth paste does not contain fluoride or only very limited amounts, because little children usually swallow the paste, they use for brushing their teeth.

Indeed, having HF on your skin can cause exceedingly painful wounds. The nasty thing is that these do not appear immediately, but only hours later at the time that you already 'forget' about the exposure. That is one of the nasty things of HF, it is not a 'honest' chem which 'bites' right now on exposure (such as Cl2 gas), but it slowly hurts, hours after the exposure, but once it starts hurting it does so in a terrible way.

If you work with HF (or solutions of NaF in acidic liquids) for chemical experiments, then you may safely assume that the concentration of HF is sufficiently high to cause serious and painful wounds. Otherwise the concentration is so low that you cannot do any interesting experiments with it :P.

evil_lurker - 2-1-2006 at 15:59

From what I hear, if you get HF on 2% of the area your skin, you will be dead.

Keep some calcium gluconate gel handy!

Fleaker - 2-1-2006 at 18:57

Hydrofluoric acid is definitely a very hazardous reagent, so much so, I know of several colleges that do not keep it on hand. If you're going to use it, have calcium gluconate gel on hand (what is it, just 2.5% gluconate, the remainder KY jelly?) If anything, the chief danger of concentrated HF is the fuming! That is what is quickly absorbed and what quickly leads to edema. Off topic, but is it true that a spill of phenol over 10 square inches will kill? I remember reading it in a chemical catalog.

oneup - 3-1-2006 at 02:02

I think i'll just put a gram or so sodium fluoride in a test tube, outside of course, pour is some concentrated sulfuric acid and run!
BTW, how do I get/make calcium gluconate? sounds like a good idea.

12AX7 - 3-1-2006 at 02:52

Hm, looks like gloconate is a mildly oxidized form of glucose, so you could get some glucose (aka dextrose), dissolve it in water, oxidize with whatever to kick the aldehyde group up to a carboxylate, then maybe crystallize the salt with sodium or potassium or something. Calcium gluconate isn't very soluble (2%) so I suppose that could be precipitated right away too, but that depends on the solubility and quantity of side products. It's listed as a chelating agent so will be good for sequestering transition ions, if you happen to have any need of that (???).

Dropping acid on NaF is a pretty stupid assed idea, not to mention useless...well it'll frost the glass, but it'll boil nicely too...

Hey Vulture, you should give him a few more posts -- he's clearly not harmless but a hazard to himself :P

Tim

[Edited on 1-3-2006 by 12AX7]

oneup - 3-1-2006 at 03:16

Can I oxidize the glucose with potassium permanganate? or nitric acid?.
I'm thinking of this:
first dissolve glucose in water, oxidize it with acidified permanganate/nitric acid
precipitate the calcium salt with a calcium base.

neutrino - 3-1-2006 at 03:21

This thread may be of some help:

Calcium Gluconate Preparation

Pyrovus - 3-1-2006 at 06:47

Not that I'd touch HF in a million years, but just out of interest would other soluble calcium salts have the same effect at treating HF burns? I assume the idea is to get rid of the fluoride ions by precipitating as CaF2?

woelen - 3-1-2006 at 14:27

Are you mad, Oneup? Adding a whole gram of NaF to concentrated H2SO4? Take much less! That is more than enough for your wanted effect. If you want to see what HF does to glass, have a look at an experiment I did with this.

http://woelen.homescience.net/science/chem/exps/KMnO4+NaF+H2SO4/index.html

If you do this experiment, I really want to urge you to use the small quantities I mention at my site and not scale up things to 1 gram!! :o!!! Also do the experiment in a WELL ventilated area. If you have any doubt about the ventilation, do the experiment outside!


EDIT(woelen): Changed link, so that it works again.

[Edited on 17-1-13 by woelen]

oneup - 4-1-2006 at 01:05

Wow. that's impressive. but where's the KMnO4 for?

12AX7 - 4-1-2006 at 02:27

Uh...it's a demonstration of a permanganate complex. The KMnO4 supplies the Mn(7+)...

Tim

neutrino - 4-1-2006 at 03:31

woelen, I'm a little confused. On the page you lined to, you referred to hydrogen fluoride and hydrofluoric acid as two different compounds. Aren't they both just HF?

oneup - 4-1-2006 at 03:42

hydrogen fluoride is the gas, hydrofluoric acid is just hydrogen fluoride dissolved in water. just like with HCl. Hydrogen Chloride is the gas, Hydrochloric acid is HCl dissolved in water.

woelen - 4-1-2006 at 10:13

Quote:
Originally posted by oneup
Wow. that's impressive. but where's the KMnO4 for?

This experiment originally was meant to see if manganese forms manganyl (VII) compounds with fluoride, just as chromium forms chromyl (VI) compounds (Cr2O2F2 and Cr2O2Cl2). I was just wondering, so I tried. The experiment confirms this. As a side reaction I also observed the intense corrosiveness of the wet HF and when I observed that, I decided to put this quite impressive experiment on my website :D.

So, if you just want to see glass eaten away, take a spatula of NaF, add 0.2 to 0.3 ml of conc. H2SO4, heat a little (to 60 C) and then add a drop of water, which you let run along the glass.

oneup - 4-1-2006 at 11:12

I will try the experiment next week as i don't have NaF yet.
I think doing it outside/near an open window would be a good idea.

IrC - 4-1-2006 at 12:05

I don't want to sound rude but playing with HF with your obvious lack of knowledge and experience on the subject sounds dumber than a box of rocks if you ask me. You are talking about one chemical so dangerous virtually every university on the planet has removed it from storage, and only stock it for specific projects and even then only allow certain specially trained people to deal with it. Near the window? Which way is the wind blowing? I just hate to see the loss of an up and coming new mad scientist, so I will say goodbye to you now while the chance still exists.

You might do a study of the effects on your heart of hypocalcemia, that is when all the calcium in your bloodstream is bound up and nerve impulses telling your heart to beat are no longer there. Not to mention amputation of limbs when your bones have been converted to calcium fluoride.

http://www.inchem.org/documents/pims/chemical/hydfluor.htm

I strongly urge you to print this out and glue it to your forehead, only to be removed when you have memorized every word therein.

oneup - 4-1-2006 at 12:28

Well, woelen is still alive.... :P:D

IrC - 4-1-2006 at 14:18

"Well, woelen is still alive."

If so I imagine he has a very good understanding of what he is doing and treats HF with the utmost care and respect. Somehow I doubt he would ever work with this stuff near a window trusting to luck that the air was flowing out instead of in. Likely he works on it with nitrile gloves, proper gear, fume hood containment with positive airflow out of the building, and carefully plans each move he makes.

Either that or he is really lucky so far.

Magpie - 4-1-2006 at 14:32

By their very nature kewls are an endangered species. As IrC has pointed out they are broodstock for mad scientists. As such we cannot afford to needlessly let them kill themselves.

I think that the members of this board have done a really good job of warning oneup about what a lethal substance he is contemplating toying around with.

oneup - 4-1-2006 at 14:52

Quote:
Originally posted by Magpie
I think that the members of this board have done a really good job of warning oneup about what a lethal substance he is contemplating toying around with.

Well, they did:P don't really think i'm gonna do this anymore... HF is probably even more dangerous then nitroglycerin, altough i've made it over and over again and still have all 10 fingers.

chromium - 4-1-2006 at 14:53

Thanks to IrC for Pim link. Very usefull. It seems that HF fumes are not so deadly as spilling it to the skin. Almost sole reason of its incredible toxicity is ability to precipitate all calcium in your blood, and skin is not barrier for HF.

Calcium gluconate is not only substance that can be used to neutralise HF on your skin. Magnesium sulfate solution is mentioned several times and all soluble calcium salts probably work. Maybe even calcium acetate that can be made by neutralisation of vinegar with lime. Soda that you use in case of other acids is not effective here as problem is not acidity of HF but its ability to precipitate calcium.

There is one more safety concern that no one mentioned so far. If there is reaction with some gaseous products then some amounts of liquid will be sprayed onto nearby things. Its not enough if you just do not drop anything onto yourself. Outer surface of test tube, stative clamp and even tabletop may also get contaminated. Do not expect that all small drops will be seen. So you need to clean everything very carefully before you (or anyone else) can touch anything without gloves.


[Edited on 4-1-2006 by chromium]

garage chemist - 4-1-2006 at 15:05

Hydrofluoric acid is very useful, it gives many reactions that the other hydrogen halide acids don't give.

For example the formation of fluoroboric acid: dissolve a stochiometric amount of boric acid in 40% hydrofluoric acid (caution: exothermic!), and after 24 hours you can fill the solution of HBF4 into a glass bottle for storage. It contains absolutely no HF any more.
The solubilities of the alkali fluoroborates are nearly the same as those of the corresponding perchlorates: the potassium salt has very low solubility.

I once performed the preparation of potassium fluoroborate (from Schlessinger Inorganic Laboratory preparations), using 40% HF. I got the HF from my dad who uses it at work (though very seldom) and brought me some. He knows that I am able to handle it safely.
I used a face shield (motorbike helmet) and gloves made of butyl rubber during the preparation, and worked under the fume hood.
However, 40% HF does not fume visibly at room temperature.
Only the 70% acid strongly outgasses HF.
I dissolved the H3BO3 in the HF (measured quantities), it got quite warm and I had to stop during the addition in order to wait for the solution to cool down, as it began fuming.
After complete addition of the H3BO3 I let it stand over night and the next day added K2CO3 solution.
The KBF4 precpitated, although it was not visible snce the refractive indices of water and KBF4 are nearly the same.
After filtration it was apparent that the yield was excellent (over 95%, since the solution was very cold).

By heating potassium fluoroborate with boric oxide (B2O3), boron trifluoride gas is produced in good yield (see Brauer for a procedure) which can be dissolved in diethyl ether to form the etherate. I haven't tried this yet, the KBF4 still sits on my shelf.

[Edited on 4-1-2006 by garage chemist]

IrC - 4-1-2006 at 17:05

http://www.inchem.org/pages/pims.html

To see others check out this link. I find them so much better than MSDS. I just wish this pim page listed more chemicals than it does. I remember reading somewhere that hydrofluoric acid starts fuming at 48 percent.

woelen - 5-1-2006 at 10:47

Quote:
Originally posted by IrC
"Well, woelen is still alive."

If so I imagine he has a very good understanding of what he is doing and treats HF with the utmost care and respect. Somehow I doubt he would ever work with this stuff near a window trusting to luck that the air was flowing out instead of in. Likely he works on it with nitrile gloves, proper gear, fume hood containment with positive airflow out of the building, and carefully plans each move he makes.

Either that or he is really lucky so far.

Yes, I'm still alive, or is this my avatar posting here?? :D :D.

To put things seriously. If you ever do an experiment with HF, only use mg quantities. In my experiment I only used 100 mg NaF, resulting in formation of appr. 45 mg of HF. Most of this remains in the liquid and in the test tube, so the amount, escaping into the air is limited to a few mg.

Besides that, I used the following safety measurements:
The experiment was performed under a fume hood, which guarantees that air is blown outwards, so there cannot be buildup of fumes.
The test tube was not taken in my hand. Not even when I wear gloves, I take a test tube with HF in it in my hands. I used a clamp to hold the test tube. This is something which I mostly do with dangerous stuff.
After the experiment was done, I immersed the test tube under water in a large tub at once, diluting and cooling down the acid immediately. The clamp was rinsed at its end carefully.

But, the single most important thing is to use small quantities. Also on my site I mention several times not to scale up the experiment.

Something which I also are very precise at is preventing long-term low-level exposures. I'm very careful not to contaminate my work area with chemicals. So, I take a lot of time and a lot of water for cleaning up, when I'm done with an experiment.

oneup - 5-1-2006 at 10:53

You should actually go to some kind of remote place, put a big glass jar on the ground, put in a kilo of NaF in it, position a flask with a litre or so sulfuric acid and some kind of system so you can mix the chems 500m away. now that would be impressive!:D

IrC - 5-1-2006 at 15:42

Oneup it sounds like you may have missed the point, and that is do it a little at a time with the proper planning and protection. Why make a bunch of HF anyway? Only have around just the amount needed for an experiment and no more, doing small amounts in each experiment. Woolen even carefully cleans up between each thing he does, and this is along with the other things he mentioned. Reading his writing here and on his website tells me he is one hell of a good researcher who plans and does everything carefully and with complete knowledge. Before you start doing things in chemistry you must first develop these skills and practises. Chemistry will do you no good without first learning safety.

I am not trying to be a boring lecturer here but your last post tells me that you still need to work on the kewlness factor.

oneup - 6-1-2006 at 00:42

I wasn't serious:P

DrP - 6-1-2006 at 02:33

I needed a high temp resistant polymer for a test I was doing - I thought about using PTFE - this would be great, however I believe that HF is generated when the stuff burns and that it has a habbit of dissolving furnace linings apparently (being SiO2) :(.

This can't be very concentrated as I've heard the effects of being near to burning PTFE lead to something they call polymer flu (rather than death) - like the flu but much much worse. I got some samples of a PTFE emulsion but decided not to go ahead with the experiments just in case.

Also - parrots and budgies kept in kitchins have died due to PTFE linings degrading from saucepans and frying pans giving small amounts of HF.

12AX7 - 6-1-2006 at 03:32

Although I'm sure HF is present in small amounts, Teflon decomposition is mostly a hodge-podge of perfluoroalkanes and -enes, with varying amounts of oxygen and hydrogen depending on conditions I'm sure. Nothing healthy at any rate.

Tim

Endo - 6-1-2006 at 07:11

I use HF almost weekly to prepare samples when assaying them for TiO2 content. We dissolve/digest an ashed sample in a mixture of 45% HF and HCl warm it to dryness and redissolve in HCl prior to analysis by AA.

It is a very useful acid, because it can dissolve the refractory metal oxides that normally are not touched by most acids. I have always used it in a fume hood, with calcium gluconate at hand.

Containers usually are made of PEEK or Teflon, and our digestion happens in a platinum crucible.

I did get some on my hand once, (it had spattered from a crucible out of the fume hood, sash was up a few inches) I knew what it was and immediately got it under the faucet, probably 2-3 seconds max, I washed it for around 20 min and then put on calcium gluconate. I escaped with a rough little sore that took a couple weeks to heal.

I have a co worker who got a hole in his glove while mixing solutions to clean silica depostits from a boiler. He got a drop on the tip of a finger and dealt with the excruciating pain for several days afterward... and yes the fingernail fell off.

I think there are commercially available paints that turn from a dark blue to yellow when HF is in contact with them, in fact the HF from Fisher sci has all the labeling done with this paint so you can tell if someone has dribbled some down the side of the bottle. I wonder what reaction it uses, I know it is reversable because the paint changes back to blue after you wash the bottle off.

:)

Ron - 28-3-2006 at 20:50

Oneup, you have been pointed in the direction of some fine information regarding the dangers of this chemical but just in case you havn't read the important bits here's something you may have missed:

Hydroflouric acid doesn't just burn. IT DISOLVES YOUR BONES!!!

Also, you may end up needing to have the calcium gluconate injected subcutaneously. Bugger that(as they say).

I just realised this thread is a bit old but I'll leave this post here anyways. Any noobs who aren't familiar with the ever-charming bone dissolving action of hf acid may benefit from seeing it in black and white.

[Edited on 29-3-2006 by Ron]

[Edited on 29-3-2006 by Ron]

purifiy to H2SO4 from H2SO4- HF solution

atabilgin - 30-3-2006 at 07:21

help me please!!!
how can I purify to sulfuric acid from H2SO4 - HF solution?
Do you know a method at this subject?

12AX7 - 30-3-2006 at 10:06

Add some calcium hydroxide. Calcium fluoride is less soluble than calcium sulfate (mind that CaSO4 is still pretty insoluble, so don't overdo it).

Tim

woelen - 2-4-2006 at 10:55

If you don't mind loosing the HF, then you could heat the liquid and keep it boiling for quite a while. The HF boils away, together with most water. What remains is 96% H2SO4 (the azeotrope with water).

Keep in mind though that this operation is VERY dangerous. This MUST be done outside or in a good fumehood, because all HF is expelled from the liquid as gas and this stuff is really toxic!
Also keep in mind, that you need a special vessel to perform this reaction in. Glass is attacked by the liquid, containing HF, especially when it is hot. You need some vessel, which withstands HF and on the other hand it also should withstand very hot sulphuric acid. I'm not sure, which material withstands both conditions, probably you need some teflon coated vessel.

12AX7 - 2-4-2006 at 13:47

Wouldn't lead do it? I mean, until you reach sulfuric acid's boiling point and it melts...(pretty close there if I recall correctly!)

Checked, H2SO4 actually boils just 10C above pure lead's melting point, LOL!

Tim

neutrino - 2-4-2006 at 16:46

Large amounts of HF gas are not to be played around with. One whiff and you're good as dead. Let's not forget about those downwind of us. I hope you live out in the middle of nowhere.

Especially if you live in the US, you risk the effects of public paranoia. I'm sure we are all familiar with those.

A likely headline:
"Terrorist unleashes chemical attack on city"

I wish I were kidding...

IrC - 2-4-2006 at 21:15

Why couldn't you bubble the HF gas through a trap full of water half filled with CaCO3 chips, turning the HF into Calcium Fluoride as fast as it is produced?

chromium - 2-4-2006 at 21:49

If this is Na2CO3 solution with CaCO3 chips then it will work even beter as dissolved Na2CO3 gets better contact with HF. This will also give CaF2 as product because it has far lower solubility than NaF.

Anyway this is rather dangerous and i would not do this without lot of thinking and experimenting with setup before puting HF containing substances into it.

[Edited on 3-4-2006 by chromium]

IrC - 3-4-2006 at 01:52

No doubt anything involving HF is dangerous, but the idea seemed better than just venting HF into the air outside. I like the addition you suggested as it would make an even more efficient HF scrubber. Coming up with the materials for the plumbing and vessels would also be problematic insofar as anything HF is concerned. Myself I just have no desire to play with HF, the 125 ml bottle of it I bought is double contained and I have never found a use for it. I bought it when I was thinking about ways to get some actinides from ores and decided against the entire idea after much study. The more I read about HF and it dangers, and the real materials problems in dealing with it, the less I liked the idea of doing any experiments with it.

At some point in time I started not wanting to own chemicals which had real problems when it came to disposing of them. I got rid of my ammonium biflouride as it could be shipped to someone who could use it but the HF was merely mailed to me in a bottle in a box with some peanuts around it. After looking into the postal regulations I realized what an idiot the guy who sold it to me was, and no way was I going to take such risks with some poor innocent mail carrier. I read about the New York trash collector who died after breathing the fumes from a bottle of 49 percent Hf which some high school kid had thrown away. He was the man who rode the truck on the back picking up the cans and as the load was squished the bottle burst and the fumes killed him. Just imagine being responsible for killing an innocent soul. I still wonder if the kid knew he had killed someone when I think about that story.

atabilgin - 5-4-2006 at 11:03

thanks! for evrytings...I will try carefully

FatihTaskiran - 6-4-2006 at 01:06

oguz I have already tried it but I don't would lıke to decompose h2so4 and hf I would lıke to purify them because we use these acids and we neutralıze naoh (%48)
thank you very much your help
if you find what I said, can you call me? you know I said if there are some company whıch they use thıs mixture we can sell ok see you soon byee

atabilgin - 6-4-2006 at 13:04

hi! mr.taskiran
if I find I will call you. ( can you speak turkish?)

FatihTaskiran - 10-4-2006 at 22:19

how are you my frıend?
Is there any news for me? I try to fınd somewhere whıch using that mıxed.
see you later byee

Madandcrazy - 19-4-2006 at 08:18

Eventually a good method beside the acid method ;) is when a NaF/H2O mix is in a big glas beaker treated per electrolysis with two carbide electrodes and a stong DC-Power Supply to get flourin and dilute HF.
The dilute acid can easy filtered off or the fluorine gas is bubbled through a nextbeaker with H2O.

[Edited on 19-4-2006 by Madandcrazy]

woelen - 19-4-2006 at 09:31

What you tell is not true. Fluorine cannot be made from aqueous solution. Fluorine immediately reacts with water, giving HF and oxygen. Fluorine can only be obtained from molten fluorides or from solutions of fluoride-salts in liquid HF.

What you tell can indeed be done with chlorine, made from dilute HCl. But for chlorine there are other faster methods of preparation.

garage chemist - 19-4-2006 at 12:35

If it is going right, I will at some point in the future present a non- electrochemical method to make fluorine, relying on the thermal decomposition of tripotassium-monohydro-ortho-fluoroplumbate.
This compound contains lead(IV), and on strong heating, it decomposes into lead(II)compound under release of fluorine.
I already have the method for synthesizing this compound.

One needs a lot of concentrated HF solution (40%) for its preparation. It will put my bottle of HF to very good use.

woelen - 19-4-2006 at 13:42

There is another method of making fluorine without the need of electrolysis. This is by formation of K2MnF6, which easily decomposes, giving KF, MnF3 and F2. This compound K2MnF6 can be formed by mixing KMnO4, HF and SbF5. Especially the latter is not an easily obtained chemical, but I mention this just as a curiousity.

flarityj - 12-5-2006 at 09:00

Hi All:

This is my first post to your group. You are a lot of fun. However, you have greatly discouraged me from experimenting with a practical use of F gas to create a barrier inside my bike's HPDE gas tank.

I know it is widely used because of this website:
http://www.fluoroseal.com/

However, they want to charge me $350 minimum and that is to cover 100 tanks. But I guess my life is worth that much.

Joe
Buckley, WA

rot - 14-5-2006 at 00:39

How actually is Fluorine gas made? and what are it's properties?

12AX7 - 14-5-2006 at 03:38

Electrolysis of KF + HF in a copper apparatus is pretty common. Some salts can be heated, also (CoF3 isn't particularly stable IIRC).

Properties? Yellowish, slightly heavier than air, reactive as FUCK... :P

Tim

Nerro - 14-5-2006 at 04:20

I'm starting to wonder how reactive it really is. Chlorine is also reactive as fuck (not FUCK but fuck) but when I dropped shards of freshly ploished metals into stoppered flasks with chlorine gas in the most of the metals did not react very hard.

neutrino - 14-5-2006 at 06:28

Chlorine isn't nearly as reactive as fluorine. Just look at the electronegativities: F is 4.0, while Cl is only ~3.1. Even oxygen is 3.5.

Chlorine will react with metals, but not as easily as fluorine. Chlorine can be stored in a stainless steel tank without problem. Fluorine, on the other hand, will ignite glass. :o Controlled chlorination reactions are possible, but fluorination...well, that doesn't work so well.

To sum it up, chlorine isn't anywhere near as reactive as fluorine. Few things are, for that matter.

[Edited on 14-5-2006 by neutrino]

woelen - 14-5-2006 at 09:53

Chlorine is a children's toy compared to chlorine. If you would call fluorine just 'reactive', then I would call chlorine 'inert'.

Sandmeyer - 15-5-2006 at 05:59

Didn't read the whole thread, anyways 1 part calcium gluconate 1 part sterile saline mixed, giving 5% calcium gluconate should be kept handy when working with HF, also a sharp knife/scalpel so that you can split the nail in case HF gets under the nail then apply the calcium gluconate saline on the flesh, this must be done fast and without hesitation...

I'm not sure what materials can take it, but following is synthesis of fluoroboric acid

Ethereal fluoboric acid can be prepared as follows: 19 ml. (19 g., 0.95 mole) of anhydrous hydrofluoric acid, b.p. 19.4° (760 mm.) is added in small portions with shaking or stirring to 126 ml. (142 g., 1.00 mole) of distilled boron trifluoride etherate, b.p. 126° (760 mm.), contained in a 500-ml. polyethylene flask that is cooled in an ice bath to 0°. The concentration of the resulting yellowish solution of fluoboric acid in ether is about 52% by weight (ca. 6.6 moles per l.).


"Whilst sitting at a fume cupboard processing mineral samples a laboratory technician knocked approximately 100 mls of hydrofluoric acid onto his thighs. Immediate 10% body burns ensued. Despite rapid flushing with water and emergency hospitalisation he died 15 days later. "

http://www.safetyline.wa.gov.au/pagebin/pg001383.htm

[Edited on 15-5-2006 by Sandmeyer]

franklyn - 28-8-2006 at 19:01

I have used a product called "whink rust stain remover" to remove iron stains
from clothing, made of 2 - 3% hydrofluoric acid. I did not heed the precautions
"causes burns which do not heal and may not be immediately painful or visible"
and I carelessly applied it without concern. Not thinking , with my finger wet
with the cleaner, I rubbed my forehead to scratch myself between my brows.
It's twelve years later and I still have the same slightly reddish skin blotch
which later developed. The fluorine combines with the calcium electrolyte of
your skin cells and remains embedded there as calcite. The prospect of
whiffing this into your lungs should make you think hard on what precautions
to take. See MSDS -> http://www.whink.com/msdsrr.pdf

[Edited on 29-8-2006 by franklyn]

not_important - 28-8-2006 at 21:01

Quote:
... The fluorine combines with the calcium electrolyte of
your skin cells and remains embedded there as calcite. The prospect of whiffing this into your lungs should make you think hard on what precautions to take. See MSDS -> http://www.whink.com/msdsrr.pdf


Fluorite or fluorspar, CaF2, note calcite. Otherwise, I agree - be carefull around F2, HF (well, HnFn), metal fluorides where the metal is in a higher oxidation state, and any fluorides that react with water (HF again).

Another have-at-hand first aid for HF accidents was/is a mix of MgO and CaCO3, wet with CaCl2 solution. Same general idea, convert HF to an insoluble fluoride - Mg and Ca, mop up any other acid around.

A test for fluorine, used to see if it was being generated or not all reacting, was to put a bit of elemental silicon into the gas stream, the Si ignites if there is much fluorine there. There are better and safer tests than this.

woelen - 28-8-2006 at 22:37

Franklyn, that sounds really nasty. Just a 2 .. 3% solution of HF, which does this nasty thing. I warned about playing with fluorides, but this is even nastier than I expected.

I have quite some NaF, but I'm VERY careful with that. The salt itself is not that dangerous, but any acid may release HF, even weak organic acids. HF itself also is a weak acid, so it is easily released.

I also noticed, that solutions of NaF do attack glass, albeit very slowly. The glass becomes somewhat milky and cannot be made fully clear again. This is an indication of hydrolysis of F(-) ions to HF, which in turn attacks the glass. So, I do not do experiments with NaF in new test tubes, I use the ones, which are somewhat spoiled anyway.

franklyn - 31-8-2006 at 21:31

http://www.sciencemadness.org/talk/viewthread.php?tid=6261#p...

Hydrofluoric Acid
All forms - dilute or concentrated solutions or the vapor - of hydrofluoric acid (HF) cause severe
burns. Inhalation of anhydrous HF or HF mist or vapors can cause severe respiratory tract
irritation that may be fatal. Death from pulmonary edema occurred within 2 hours in three of six
workers splashed with 70% HF solution despite prompt showering with water. Anhydrous HF is a
clear, colorless liquid that boils at 19.5o C. Because of its low boiling point and high vapor
pressure, anhydrous HF must be stored in pressure containers. A 70% aqueous solution is a
common form of HF. Hydrofluoric acid is miscible with water in all proportions and forms an
azeotrope (38.3% HF) that boils at 112o C. Anhydrous or concentrated aqueous HF causes
immediate and serious burns to any part of the body. Dilute solutions (<30%) and gaseous HF are
also harmful, although several hours may pass before redness or a burning sensation is noticed.
These burns may still by quite severe and progressively damaging to the skin and deeper tissues.
"Undissociated HF readily penetrates skin and deep tissue where the corrosive fluoride ion can
cause necrosis of soft tissues and decalcification of bone; the destruction produced is
excruciatingly painful. Fluoride ion also attacks enzymes (e.g. of glycolysis) and cell membranes.
The process of tissue destruction and neutralization of the hydrofluoric acid is prolonged for days,
unlike other acids that are rapidly neutralized. Because of the insidious manner of penetration, a
relatively mild or minor exposure can cause a serious burn" [Proctor, N. H.; Hughes, J. P.;
Fischman, M. L. Chemical Hazards of the Workplace, J. B. Lippincott Co., Philadelphia, 1988,
p.279]. Occasionally workers fail to recognize the importance of seeking medical attention for HF
before pain commences. By the time the victim is affected with progressively deep and more
painful throbbing and burning, serious damage may have taken place. Exposures under
fingernails can be a particularly painful problem if ignored. Wearing clothing (including leather
shoes and gloves) that has absorbed small amounts of HF can result in serious delayed effects
such as painful slow-healing skin ulcers.
When handling HF, it is crucial to ensure adequate ventilation by working only in a hood so that
safe levels (3 ppm) are not exceeded. All contact of the vapor of the liquid with eyes, skin,
respiratory system, or digestive system must be avoided by using protective equipment such as a
face shield and neoprene or polyvinyl chloride gloves. The protective equipment should be
washed after each use to remove any HF on it. Safety showers and eyewash fountains should be
nearby. Anyone working with HF should have received prior instructions about its hazards and in
proper protective measures and should know the recommended procedure for treatment in the
event of exposure (Reinhardt, C.F> et al.; Am. Ind. Hyg. Assn. J., 1966, 27, 166.)
Spills and leaks - The vapors of both anhydrous HF and aqueous 70% HF produce visible fumes
if they contact moist air. This characteristic can be useful in detecting leaks but cannot be relied
on because of atmospheric variations. Spills of HF must be treated immediately to minimize the
dangers of vapor inhalation, body contact, corrosion of equipment, and possible generation of
hazardous gases. Spills should be contained and diluted with water. The resulting solution should
be neutralized with lime before disposal.
Waste disposal - Waste HF should be slowly added to a larger volume of a stirred solution of
slaked lime to precipitate calcium fluoride, which is chemically inert and poses little toxic hazard
(sodium fluoride is highly soluble and toxic). Alternatively, hydrofluoric acid can be diluted to
about 2% concentration with cold water in a polyethylene vessel, neutralized with aqueous
sodium hydroxide, and treated with excess calcium chloride solution to precipitate calcium
fluoride.
In the event of exposure - Anyone who knows or even suspects that he or she has come into direct
contact with HF should immediately flush the exposed area with large quantities of cool water.
Exposed clothing should be removed as quickly as possible while flushing. Medical attention
should be obtained promptly, even if the injury appears slight. On the way to the physician, the
burned area should be immersed in a mixture of ice and water. If immersion is impractical, a
compress made by inserting ice cubes between layers of gauze should be used. Make sure that the
physician understands that the injury was cause by HF and requires treatment very different from
other acid burns. Even in the case of very small exposure, washing alone may not be sufficient to
completely prevent injury. For minor exposures such as small hole in glove, application of a
calcium glutaconate antidote gel can bind free fluoride ion not removed by washing.
If HF liquid or vapor has contacted the eyes, these organs should be flushed with large quantities
of clean water while the eyelids are held apart. This flushing should be continued for 15 minutes.
Medical attention should be obtained promptly.
Anyone who has inhaled HF vapor should be removed immediately to an uncontaminated
atmosphere and kept warm. Medical help should be obtained promptly. Anyone who has ingested
HF should drink a large quantity of water as quickly as possible. Do not induce vomiting. Again,
medical help should be obtained promptly. After the acid has been thoroughly diluted with water,
if medical attention is delayed, the person should be given milk or two fluid ounces of milk of
magnesia to drink to sooth the burning effect.

.

[Edited on 24-7-2007 by franklyn]

fdnjj6 - 13-8-2020 at 17:26

Quote: Originally posted by oneup  
I think i'll just put a gram or so sodium fluoride in a test tube, outside of course, pour is some concentrated sulfuric acid and run!
BTW, how do I get/make calcium gluconate? sounds like a good idea.


Ah yes, let's just expose the neighbors and everyone around you to it. Stop fucking with chemicals like that.

I know this was years ago but this is just to serve as a warning to others. Outside =/= fume hood.

symboom - 13-8-2020 at 18:18

Quote: Originally posted by woelen  
What you tell is not true. Fluorine cannot be made from aqueous solution. Fluorine immediately reacts with water, giving HF and oxygen. Fluorine can only be obtained from molten fluorides or from solutions of fluoride-salts in liquid HF.

What you tell can indeed be done with chlorine, made from dilute HCl. But for chlorine there are other faster methods of preparation.


Oh that's right fluorine reacts with water forming HF damn it sounds like it's reactive like sodium metal except being electronegative the only way I could see getting around it is desolving the salt in a low melting Flourine based eutetic ionic solution